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Browse Prior Art Database

IN SITU IC TEST SOCKET

IP.com Disclosure Number: IPCOM000009428D
Original Publication Date: 1999-Sep-01
Included in the Prior Art Database: 2002-Aug-22
Document File: 2 page(s) / 129K

Publishing Venue

Motorola

Related People

Adolph Naujoks: AUTHOR

Abstract

An interface method is described, which facili- tates the testing of ICs that are packaged on sub- strates with C5 interconnects. The IC contact method is based on a conformable, anisotropic inter- connect, which provides excellent rf characteristics in a frequency range from dc to 3 GHz.

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MOTOROLA Technical Developments

IN SITU IC TEST SOCKET

by Adolph Naujoks

ABSTRACT

  An interface method is described, which facili- tates the testing of ICs that are packaged on sub- strates with C5 interconnects. The IC contact method is based on a conformable, anisotropic inter- connect, which provides excellent rf characteristics in a frequency range from dc to 3 GHz.

INTRODUCTION

  The need for a rapid performance evaluation of KS, which are suspected of causing malfunctions in portable radios, led to the development of the in situ test socket described in this article. This IC socket provides a method of inserting a surface mount device into the circuit environment it was designed to operate without the need for permanent soldering connections.

  The conformable interconnect socket provides a number of distinct advantages over a bed of nails or a commercial, wire leaded socket. The 0.01" thick- ness of the anisotropic interconnect minimizes the separation between the IC's contact pads and the PC board circuit, thereby significantly reducing any impedance discontinuities. In comparison, a typical separation for a pogo pin contact is 0.50 to 0.75". S-parameter measurements have shown that this complaint interface maintains excellent transmission line quality at frequencies of up to 3 GHZ.

  In addition, the interconnect's multi-point con- tacts guarantee high measurement integrity and repeatability. A typical socket contacts an IC pad at one single point only. The elastomeric interconnect can provide several separate contact points for each individual pad. The socket's contact pitch or pad to pad spacing permits contacting of devices with pad spacings as fine as 0.015".

Fig. 1

ANATOMY OF A COMPLIANT, ANISOTROPIC TEST SOCKET

  Figures 1 and 2 illustrate two different methods of fabricating the anisotropic elastomer interconnect socket. Figure 1 shows the design of a socket for an IC with C5 solder balls. The socket, in its simplest form of implementation, consists of a template with holes for a drop-in alignment of the IC's solder balls. A thin sheet of conductive, anisotropic elas- tomer, located between the template and the PC board, provides the electrical interconnect for the IC. The template aligns the solder balls of the IC to the solder pads of the PC board. The exact align- ment of the template is accomplished by guide pins or rails...